Meme: Meme is an idea that catches on.

Meta Search: Meta search is process of searching in multi databases simultaneously and combining the results.

Meta Search Engine: Meta search engine is also a search engine that sends the user request simultaneously to multi search engines, databases and combines the results.

Meta Tag: Meta tags are placed in the head section of an Html document. Search engine ranking popular Meta tags can affect.

Metacrawler: Metacrawler is one of the large Meta search engine which search other search engines.

MetaFind: MetaFind is a Meta search engine.

Mining Company: Mining company former name of About.com

Mirror Sites: A duplicate copy of a website with separate url load another server. Mirror sites are very difficult to index by search engines and search engines are spamming the multi duplicate pages.

Misspellings: Making spelling mistake intentionally in Meta tags or Meta keywords to cache the search engines for the user who misspell the words when searching.

Mulit Titles: A Mulit title is trick. To increase search engine relevancy where authors double up the titles in a webpage.

Multiple Meta Tags: Using multi keyword Meta tags to increase the relevancy of a page. Search engines are considers this technique as spam.